$A$ sample of a metal oxide has the formula $M_{0.83}O_{1.00}$. The metal $M$ can exist in two oxidation states,$+2$ and $+3$. In the sample of $M_{0.83}O_{1.00}$,the percentage of metal ions existing in the $+2$ oxidation state is $.........\%$ (nearest integer).

The volume of hydrogen liberated at $STP$ by treating $2.4 \ g$ of magnesium with excess of hydrochloric acid is $x \times 10^{-2} \ L$. Find the value of $x$. Given: Molar volume of gas is $22.4 \ L$ at $STP$. Molar mass of magnesium is $24 \ g \ mol^{-1}$.

The mass of a mixture containing $NaCl$ and $NaBr$ is $4.0 \ g$. If $Na$ is $30 \%$ of the total mixture,the composition of $NaCl$ in the mixture is (in $\%$)

$NaClO_{3}$ is used,even in spacecrafts,to produce $O_{2}.$ The daily consumption of pure $O_{2}$ by a person is $492 \ L$ at $1 \ atm, 300 \ K.$ How much amount of $NaClO_{3},$ in grams,is required to produce $O_{2}$ for the daily consumption of a person at $1 \ atm, 300 \ K?$
$2NaClO_{3(s)} + Fe_{(s)} \rightarrow 3O_{2(g)} + 2NaCl_{(s)} + FeO_{(s)}$
$R = 0.082 \ L \ atm \ mol^{-1} K^{-1}$

How many $mL$ of $0.1\, M\, HCl$ are required to react completely with $1\, g$ mixture of $Na_2CO_3$ and $NaHCO_3$ containing equimolar amounts of both?

For the given series of reactions:
$NH_{3(g)} + O_{2(g)} \rightarrow NO_{(g)} + H_2O_{(l)}$
$NO_{(g)} + O_{2(g)} \rightarrow NO_{2(g)}$
To obtain the maximum mass of $NO_2$ from a given mass of a mixture of $NH_3$ and $O_2$,the ratio of the mass of $NH_3$ to $O_2$ should be: